Resumen:
Flavorings are encapsulated through spray drying to ensure protection throughout their shelf life. However, the stability of microencapsulated flavorings largely depends on the choice of wall material. This work evaluates three wall material systems of walnut flavor: microcapsules of mesquite gum (MMG), whey protein concentrate (MWPC) and a 1:1 (w:w) mixture of both (MMG-WPC), onto their moisture sorption isotherms, fitting to GAB model, thermodynamic and sorption properties at different temperatures (25, 35 and 40°C). The MMG displayed greater monolayer moisture adsorption capacity (M0: 4.69-5.52 kg H2O/100 kg dried solid (d.s.)) and adsorbent-adsorbate interaction due to its greater hygroscopicity, but less tendency to agglomeration trend than MWPC and MMG-WPC. The MMG exhibited the lowest differential enthalpy and entropy values, promoting an advantageous dehydration process and ensuring greater stability, which was attributed to the enhancement of water molecular order. Additionally, MMG displayed the largest sorption surface area, facilitating the moisture sorption process. Therefore, all three microcapsules’ systems were able to stabilize the walnut flavor, however, their slight differences in their moisture sorption capacity led to different stabilization mechanisms that affected their shelf life.
Descripción:
In this research, walnut flavor microcapsules were evaluated using three different wall materials, mesquite gum (MMG), whey protein (MWPC) and their mixture (MMG-WPC) 1:1 mass ratio, on their moisture sorption capacity and thermodynamic properties across temperatures of 25, 35 and 40°C. All three microcapsules’ systems presented sigmoidal type II curves indicative of water adsorption occurring in both monolayer and multilayer mechanisms on their porous surfaces. However, MMG had a greater moisture adsorption capacity, showcasing stronger adsorbent-adsorbate interactions due to its greater hygroscopicity. Additionally, MMG did not exhibit agglomeration as occurred with MWPC and MMG-WPC. The MMG also showed the lowest values of differential enthalpy and entropy, favoring the dehydration process and indicating a more ordered arrangement of water molecules, contributing to enhanced system stability. Likewise, the MMG had the largest sorption surface area due to its microporous structure, facilitating and increased water sorption process and resulting in higher values of moisture content in the monolayer. All three microcapsules’ systems displayed negative free energy, indicating a spontaneous moisture adsorption process. In general, the three microcapsules’ systems can stabilize the walnut flavoring. However, the slight differences in their moisture sorption capacity and thermodynamic properties under specific moisture and temperature conditions suggest distinct stabilization mechanisms emphasizing the critical role of selecting a suitable wall material to ensure optimal protection for walnut flavoring throughout its shelf life.